glulam beam vs HEB-steel beam

[Krillew]

Help!...

Yes, I also have a small beam problem...
I'm expanding the house and will have a living room with dimensions of 7x8 meters. Now my construction manager wants me to place a steel beam across as reinforcement along with a column in the middle... That's not how I want it...

Upstairs, there will be two rooms with a wall in between, an outer wall at one end, and a load-bearing inner wall at the other...

Shouldn't the wall between the rooms be made like a beam, and you can attach joist hangers and lay the floor joists... The beam will be 2.5m high and 8m long; it should be possible to make it very stable... The floor and ceilings absorb shear forces; the floor, ceiling, and wall form a huge H-beam...

I was thinking of two plywood joists at the top and two at the bottom, then vertical OSB in between, possibly adding strap iron behind the joist hangers to handle the tensile forces...

 

[hempularen]

I can't quite envision what you (or your construction manager) mean. But if we assume it's the 7m stretch where a beam is supposed to be? It is possible to make such a beam recessed in the flooring. We have just added a floor to part of our house. We have 8 x 5m. For various reasons, the beams needed to run in the 8m direction. This was solved with 2 steel beams, each 5m long. They are HEA 160. Then the wooden beams (45 x 220) are inserted into the steel beam. So the beams are not visible. The longest span for the wooden beams is about 3.5m. The reason there were 2 beams is that there is a staircase in the middle of everything as well. Now you have a slightly longer span, but you should be able to use beams that are about 220 high without affecting the overall thickness of the flooring. Then your construction manager or another person who is good at calculations can determine the required dimensions.

It should be possible to span 7m without columns.

 

[imported_Byggaren]

Now I didn't calculate my project, but roughly estimated by rule of thumb, and took what I had on hand, and it worked, and became stronger than the previous solution that was there.

Was my years of professional welding for reinforcement and welding beams from flat iron unnecessary because desired dimensions were not available?
I guess I should visit the old workplace and tell the engineer and the guys that they are wasting their efforts...

We were talking about a 3.6 m day opening on a small villa, right?

It wasn't what you did or that it won't hold that I was trying to get you to think about, but that you have poorly utilized the material strength of the steel.

Wood is, compared to steel and regardless if it's a beam or a glulam beam, up to 20 times worse in tensile and compressive strength (depending on the quality in wood and steel). If you stand the steel up (as you have done), you utilize a maximum of 20% of the steel's total, against that you could have used 100% if you had laid a flat bar horizontally in the lower and upper parts of the beams of half the thickness and significantly narrower width (say 5x100 mm/piece), provided you could rigidly lock the ends together with a couple of welded flat bars of the same dim. around the beams.

It's always good to have worked with things practically (which many theorists have not), but it's even better to know why you do just so and so (as I do). When you have welded an I-beam of flat bars with web reinforcements, it is a consequence of the flat bars being too thin/the beam too high/long and therefore needed to be stiffened against web buckling as a result of the forces that give rise to bending moments in the profile.

The web reinforcements do not in any way affect the bending resistance in the beam. Nor the stiffness. The beam bears and bends therefore no more/less because of them, but it is solely aimed at the web in the beam not being able to buckle and twist, because then the load-bearing capacity and stiffness decrease.

So your guys on the workshop floor and in the office were probably right in their directives about web reinforcements even if they then had to hire a skilled welder (like you) to put it together

Even I can roughly see what is needed without calculating it, but if I'm at all unsure that the 'feeling' is right, I make an approximate calculation to check if it aligns. For economic reasons, I usually don't 'guess' to make it hold. That only results in over-dimensioning and unnecessary costs/weights.

If you are more interested in construction theory, I recommend you to get a textbook in statics (and possibly dynamics) of the type used in education at the secondary school level + a strength of materials and formula collections and strength tables for wood and iron. It is interesting reading, but requires some knowledge in math, even if you can manage far with arithmetic, geometry, and equation learning. You only need to be able to solve a quadratic equation with two roots at most. The rest are first-degree equations even though there can be many unknowns in such. In that case, it is just necessary to accumulate as many equations as there are unknowns and then master the art of transforming them with method substitution among others.

You can also perform a practical experiment that will likely drive you to look into the literature (strength of materials) to find the explanation for it. Take five regular plastic rulers (equally long and wide) and lay them with the flat side on one another. Pinch the ends (which should be even with each other) with both hands and then ask someone else to put a finger in the middle of the top one and slowly apply pressure. If you are observant, you might see that the previously even-laid ends have shifted relative to each other. (If nothing else, you will notice this in your fingers by holding against.) Then the question arises: what would have happened if they hadn't shifted in relation to each other? That is, the ends still had been even, which assumes that the top ruler would become shorter and the bottom one longer and the ones in between adjust in length after these two. I can also say at once that the middle one would maintain the original length.

Good luck!
_________________
Byggaren

 

[imported_Byggaren]

Help!...

Yes, I also have a small beam problem..
I am extending the house and will have a living room with dimensions of 7x8 meters, and now my CA wants me to place an iron beam across it as bracing along with a pillar in the middle... That's not how you want it all...

Upstairs, there will be two rooms with a wall in between, an outer wall at one end, and a load-bearing inner wall at the other...

Shouldn't the wall between the rooms be able to be made like a beam and where you screw in joist hangers for the floor joists... the beam will be 2.5m high and 8m long, it must be possible to make it really stable... The floor and ceilings take up the shear forces, the floor, ceiling, and wall form a gigantic H-beam....

I thought of two plywood joists on top and two at the bottom, then standing obs between, possibly placing tension straps behind the joist hangers to handle the tensile forces..

It is quite possible to make an 'inverted' beam and hang the floor structure from it instead of placing it under and putting a pillar under the middle of it. Additionally, you have the entire floor height available, which ensures that this 'beam' will be vastly stronger than a steel beam underneath.

The problem is just how you are going to make it and what loads are involved since these must be transferred down to the ends and maybe in such a small area that the buckling force becomes dimensioning. But even that can be solved by doubling the upright joists in underlying walls and in other ways.

So have a talk with your CA or hire a nearby structural engineer who can get a rough idea of what is possible to achieve. It is certainly fully feasible.

However, a particular problem arises the day the wall above is to be demolished if the rooms are to be joined either by you or future owners. Therefore, the wall should be specified as load-bearing on the building permit drawing.
___________________
The Builder

 

[Krillew]

Hello!
No, the beam should be on the 8m length... But it would be nice to install a beam without needing a crane to lift it. So the basic idea is to avoid the crane and the pillar in the middle of the room.

Yes, regarding calculations... No, or yes, I usually have issues with formulas... if I come across an interesting collection of formulas, it usually results in a program... I am a notorious programmer... (or by profession) I am currently working on a u-value calculation program... I thought it would be available for download later... (free) I have used it myself for my building permit... So if anyone tempts me with beautiful formulas, you know where it might end...

 

[imported_Byggaren]

---

Oh right... regarding calculations No or yes I tend to have problems with formulas... because if I come across an interesting collection of formulas, it usually results in a program.. I am a notorious programmer... (or by profession) --- So, if someone entices me with beautiful formulas, you know what it may end up with...

Wow! Then you have your work cut out for you. I can recommend a book series called Bygg. It contains formulas for all possible load cases. In my old Bygg, volumes I and III, they make up about 80% of the total page count (1,800 pages). But even a simpler collection of formulas for construction purposes (found in vocational high school programs) is enough for a lifetime of programming. Take, for example, the book 'Byggformler och tabeller' (originally compiled by Paul Johannesson).
______________________
Byggaren

 

[shelby67]

Now I have read the assembly instructions from hajom, so the frame headstock should also be screwed with frame sleeves type adjufix in the overhead beam. Excerpt from the instructions:

Here it is important to have the recommended 20mm clearance between the beam and the upper frame piece so that the beam in the wall opening has the opportunity to sink the 10mm tolerated in a construction calculation.

So now the choice is between a hea160 that the designer came up with in his program, or a hea180 that the builder here on the forum recommends, the price difference between them is about 565:- and I have the space, the question is whether 565:- is quite a cheap extra insurance after all, even if we are talking about over-dimensioning.

 

[imported_Byggaren]

Now I've read the installation instructions from hajom, even the frame header should be screwed with frame sleeves like adjufix in the overhead beam, Extract from the instructions:

Here it is important that you have the recommended 20mm sealing gap between the beam and the top frame so that the beam in the wall opening has the ability to settle the 10mm that is tolerated in a construction calculation.


So now the choice is between hea160 which the designer came up with in his program, or a hea 180 which the builder here on the forum recommends, the price difference between them is about 565:-
and I have the space, the question is whether 565:- is a pretty cheap extra insurance after all, even though we're talking about over-dimensioning.

If you're going to screw a lintel to a door/gate in the beam, 10 mm may be enough to prevent you from opening it, provided the fastening isn't telescopic. Then 500:- might be a pretty cheap insurance for it to be openable.
________________
The Builder

 

[Mats]

Take the 180 beam. As mentioned, it's not a lot of money and it gives you a bit of extra margin which can be good to have. Constructions usually become so expensive that you need to cut corners somewhere, but in my opinion, this is not the right place for it

 

[Krillew]

Wow! Then you have a lot to do. I can recommend a book series called Bygg. It contains formulas for all existing load cases. In my old Bygg, volumes I and III, they make up about 80% of the total page count (1,800 pages). But even a simpler collection of formulas for construction purposes (available in high school engineering education) is enough for a lifetime of programming. For example, take the book 'Byggformler och tabeller' (originally compiled by Paul Johannesson).
______________________
Byggaren

Thanks for the tip... or maybe not!! depends a bit on my time... but I will definitely check out the books... I have an old book by Hj Tallqvist from 1895!! but strength theory is probably the same today as it was then.. Could it be that you know the ISBN number for Bygg I and III? I've found the other one on liber.

 

[shelby67]

If you are going to screw an architrave to a door/gate in the beam, 10 mm may be enough for you not to be able to open it, provided that the attachment is not telescopic. Then a 500 could be a pretty cheap insurance to ensure it can be opened.
________________
Byggaren

Thank you Byggaren for your tips and advice Tomorrow I will go and buy an HE180A beam for my construction.

 

[Mäster]

It wasn't what you did or that it won't hold that I was trying to get you to think about, but that you have underutilized the material strength of the steel.

Wood, compared to steel and regardless if it is a plank or a glued-laminated beam, is up to 20 times worse in tensile and compressive strength (depending on the quality of wood and steel). If you stand the steel upright (as you have done), you use a maximum of 20% of the steel's total, whereas you could have utilized 100% if you had laid a flat bar on the flat side in the bottom edge and top edge on the beams of half the thickness and significantly narrower width (say 5x100 mm each), provided you could lock the ends to each other immovably with a couple of welded flat bars of the same dimension according to the condition of the beams.

It's always good to have worked with things practically (which many theoreticians haven't), but it's even better to be clear about why you do this and that (as I have). When you weld an I-beam of flat bars with web stiffeners, it's because the flat bars have been too thin/the beam too tall/long and therefore needed to be stiffened against web buckling due to the forces that cause bending moments in the profile.

The web stiffeners do not affect the bending resistance of the beam in any way. Nor the stiffness. The beam thus carries and bends neither more/less because of them, but it is solely to ensure the web of the beam does not buckle and twist, because then it decreases in both carrying capacity and stiffness.

So, your guys on the workshop floor and in the office were probably right in their directives about web stiffeners even if they later had to hire a skilled welder (like you) to get it together

Even I can roughly see what is needed without calculating it, but if I am unsure if my 'feeling' is right, I do an estimate calculation to check if it matches. For economic reasons, I don't usually 'guess' to make it hold. That just leads to over-dimensioning and unnecessary costs/weights.

If you're more interested in construction theory, I recommend you get a textbook in statics (and possibly dynamics) of the type used in high school education + a materials science book and formula collections and strength tables for wood and iron. It’s interesting reading but requires some math knowledge, even if you get far with arithmetic, geometry, and equation solving. You only need to solve a quadratic equation with two roots at most. The rest are first-degree equations, even if it can teem with unknowns in them. Then you just need to gather as many equations as there are unknowns and master the art of transforming them with the substitution method, etc.

You can also do a practical experiment that will probably make you turn to the literature (materials science) to find the explanation for it. Take five ordinary plastic rulers (equally long and wide) and lay them flat on each other. Pinch the ends (which should be even with each other) with both hands and ask someone else to put a finger on the middle of the top one and slowly apply pressure. If you are observant, you will see that the previously evenly laid ends have shifted relative to each other. (If nothing else, you’ll notice it in your fingers from holding them.) Then the question arises: what would have happened if they didn't shift relative to each other? That is, the ends were still even, which presupposes that the top ruler would become shorter and the bottom longer, and those in between would adjust in length according to these two. I can also immediately say that the middle one would retain its original length.

Good luck!
_________________
The Builder

"Web stiffeners do not affect the bending resistance of the beam in any way. Nor the stiffness. The beam thus carries and bends neither more/less because of them, but it is solely to ensure the web of the beam does not buckle and twist, because then it decreases in both carrying capacity and stiffness."
I don't think I claimed anything else...

Probably you misunderstood me in how I placed the flat bar, or I misunderstand what you mean,,
The iron bears the weight itself, the 2x8s I bolted on only for stiffening and to make it easier to attach to the wall, and so it wouldn't topple while I was assembling,
The solution with the flat bar came about because I had one, and the "engineer" thought like I did that it was sufficient when I went to the workshop to negotiate for a beam...
Materials science is yet another subject among many I would like to study, if only I could find the motivation...

 

[imported_Byggaren]

"The web stiffeners do not affect the bending resistance of the beam in any way. Nor the stiffness. The beam carries and bends neither more nor less because of them, but it is solely to ensure that the web in the beam cannot buckle and twist, as it would then reduce both its bearing capacity and stiffness."

I don't think I claimed otherwise...

You probably misunderstood me in how I placed the flat iron, or I misunderstand what you mean,,
The iron bears the weight itself, the 2x8's I bolted on only as reinforcement and to make it easier to attach it to the wall, and to prevent it from toppling while I was mounting it,
The solution with the flat iron came about because I had one, and the "engineer" thought like me that it would suffice, when I went to the workshop to negotiate a beam...
Strength of Materials is another subject in the multitude I would like to study if I could just find the motivation...

No. I understood what you did and used 2"x8" as reinforcement for the flat iron. The point of what I wrote was that you're only utilizing a fraction of the iron's strength and bearing capacity that way.
________________________
Byggaren

 

[Mäster]

If you ever feel at a loose end, you are welcome to post or PM a sketch of how I should have arranged it, I'm getting stuck in the text, probably because I have a preconceived opinion that "locks me up."

I know EVERYTHING... But I'm trying to learn something when the opportunity arises...